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The most critical factor in medicine? Human bias

In the summer of 2003, I finished my three-year residency in internal medicine and began a fellowship in oncology. It was an exhilarating time. The Human Genome Project had laid the foundation for the new science of genomics, the study of the entire genome. And it was nothing short of a windfall for cancer biology.

Cancer is a genetic disease, an illness caused by mutations in genes. Until the early 2000s, most scientists had examined cancer cells one gene at a time. But once we could examine thousands of genes in parallel, the true complexity of cancers became evident. The human genome has about twenty-four thousand genes in total. In some cancers, up to a hundred and twenty genes were altered — one in every two hundred genes — while in others, only two or three genes were mutated. (Why do some cancers carry such complexity, while others are genetically simpler? Even the questions were unexpected — much less the answers.)